The present invention relates to a sealing assembly for use in a rolling mill.
A rolling mill may be operated under wet conditions in which water (or other coolant) is fed over the roll. A certain amount of water is inevitably dispersed into the direction of the roll neck and the lubricated areas of the bearing assembly. A sealing assembly may be used on the tapered section of the roll neck in order to maintain a liquid barrier between the rod and the bearing assembly.
Frequently, the sealing assembly includes a coolant seal positioned on a seal end plate which is fixed to the bearing chock. The coolant seal is generally secured on a mounting surface of the seal end plate and contacts the roll end face thereby providing a barrier to ingress of coolant and contaminants into the main bearing assembly.
One such conventional sealing assembly is described in GB-A-2137701 (Morgan Construction Company). This particular arrangement comprises a coolant seal with a radially disposed mounting flange integrally joined at its inner edge to a sealing flange extending angularly and flexibly therefrom towards the roll face. The mounting flange has a series of holes through which screws may be passed and threaded into circumferentially spaced holes in the seal end plate. The mounting flange is provided with an integral circular bumper axially protruding towards the roll end face.
One drawback of the coolant seal arrangement in known bearing assemblies is that when secured in position the coolant seal fails to provide an efficient contact at the interface with the seal end plate. This may have serious consequences where water is allowed to pass between the two surfaces.
The present invention seeks to overcome this disadvantage of the prior art assemblies by improving the contact between the coolant seal and the seal end plate. In addition, the invention mounts the coolant seal more rigidly than in is possible in the prior art assemblies.
Thus viewed from one aspect the present invention provides a sealing assembly for use in conjunction with the rotatable tapered section of a roll neck which is part of a roll in a rolling mill, said sealing assembly having a first bearing element mounted on said rotatable tapered section and at least partially opposing a fixed second bearing element to define a contact surface therebetween which is adapted to receive lubricant, wherein said fixed second bearing element or said first bearing element comprises a flexible seal element axially positioned between the contact surface and the roll end face and mounted on a seal end plate, wherein the face of said seal end plate adjacent the roll end face is provided with an annular recess defined at one edge by a circular surface on a portion of the seal end plate and at the opposite edge by a circular surface of a seal retaining means (eg seal retaining plate) which is detachably secured to the seal end plate, wherein a substantially annular part of a coolant seal is mounted in the annular recess of the seal end plate.
The sealing assembly of the invention improves the efficiency of the coolant seal by providing a reliable and rigid mounting surface on the seal end plate. The absence of separate fasteners for fastening the coolant seal to the seal end plate adds to the improved efficiency of the coolant seal. It is well known in the art that the outermost circumferential edge of the seal end plate undergoes wear during axial xe2x80x9cfloatingxe2x80x9d of the assembly in use. An added benefit of the assembly according to the invention is that when the seal retaining means has worn it may be readily removed and replaced cheaply.
In a preferred embodiment, the circular surface on the seal end plate is provided by a circular shoulder or flange axially disposed on the face of the seal end plate adjacent to the roll end face.
In one embodiment, the seal retaining means is secured proximate the outer circumferential edge of the seal end plate. Preferably, the seal retaining means comprises a substantially L-shaped cross-section which serves to encapsulate the outermost circumferential edge of the substantially annular part of the coolant seal. The base of the substantially L-shaped cross-section is preferably thickened and adapted to receive a fastener (eg a screw)
Preferably, the coolant seal comprises a radially disposed, annular mounting flange adapted to be mounted in the annular recess of the seal end plate. Particularly preferably, the annular mounting flange comprises a planar rear surface and a planar or curved front surface.
Preferably, the coolant seal comprises a sealing flange angularly disposed from the inner edge of the annular mounting flange. The sealing flange is advantageously non-uniform between its sealing contact point at the roll end face and the portion connected to the mounting flange. This helps to maintain the sealing contact. The section between the contact point and the connecting portion is conveniently thickened to stiffen the sealing flange and minimise bending. Preferably the root of the sealing flange is provided with a circumferential notch which assists in minimising local distortion of the mounting flange during rotation due to axial movement of the roll end face.
In one embodiment, the flexible seal element is mounted on the fixed second bearing element. The fixed second bearing element therefore comprises the seal end plate upon which the seal element is mounted.
Preferably, the flexible seal element comprises a substantially annular body and one or more (preferably two) circumferential lips inwardly disposed from the substantially annular body. Particularly preferably, the or each inwardly disposed circumferential lip is angularly disposed. Especially preferably, the or each circumferential lip is attached at the central section of the substantially annular body. For example, each circumferential lip may be attached by shoulders radially raised on the inner surface of the annular body and conveniently axially spaced apart. Preferably the seal element is substantially axially symmetrical. A lantern ring may be incorporated in the seal element to drain out any oil which does penetrate the seal element.
In the preferred embodiment, the or each circumferential lip is provided with an enlarged peripheral end. Preferably, the enlarged peripheral end is multi-faceted. For example, the enlarged peripheral end may comprise five annular faces. Preferably the enlarged peripheral end is provided with a reduced point arranged to contact the first bearing element in use. In use, the circumferential lips of the flexible seal element may be deformable in order to adopt a stressed state. The force acting in opposition to the stressing may improve the seal between the peripheral end of the lips and the contact surface. The peripheral end may be conveniently provided with a cut-away portion for encapsulating a garter spring which may further improve the seal.
In the preferred embodiment of the invention, the peripheral end of the or each circumferential lip is seated on the first bearing element of the sealing assembly. For this purpose, the first bearing element may be provided with a carrier ring mounted on the tapered portion of the roll neck and providing a substantially horizontal running surface. Preferably, the carrier ring is coated with a metal coating, particularly preferably a chrome coating which acts as the horizontal running surface. This is advantageous over conventional ceramic-based coatings which have been found to lead to significant deterioration of the seal element and which are unable to remove the significant amounts of heat which are generated. In the latter regard, chrome possesses excellent heat dissipation properties.
The seal end plate may comprise an axial recess (eg an annular recess) in which at least the annular body of the flexible seal element is located. On the roll side, the seal end plate may be provided with a clamp for retaining the seal element in the recess. One inner face of the clamp advantageously forms the outer face of the recess in which the seal element is located thereby permitting easy access to the recess for installation/removal of the seal element and visual checking of the seal element. The clamp may be provided with an appropriate fastener for ease of removal.
The seal end plate may be mounted adjacent and attached to the chock on the non-roll side. Conventional fastening means may be appropriate for this purpose. In one embodiment, the seal end plate comprises a plurality of spaced apart apertures capable of receiving fastening means for securing the seal end plate to the chock. Preferably the openings of the plurality of apertures are located in the annular recess.
In accordance with the invention, the first bearing element preferably comprises a sleeve mounted on the rotatable roll neck in a conventional manner (eg keyed). The fixed second bearing element preferably comprises a fixed bushing carried in a bearing chock. The sleeve is conveniently provided with an outer surface which is adapted to be rotatable within an inner surface of the fixed bushing thereby defining the contact surface at the axial side of the seal element opposite to the roll side. Lubricant is fed to the contact surface and an extended portion of the chock may conveniently serve as an oil reservoir for drainage and re-circulation purposes.